Friday’s announcement of St. Paul’s soccer stadium plans was one of the final pieces to Minnesota’s MLS puzzle. Left unanswered, at least for the time being, is the question of whether Minnesota will join the league in 2017 or 2018. It’s important, because if United will join the league in 2017, its first steps toward building an expansion squad will be taken this winter.

When MLS announced Minnesota would join the league, Commissioner Don Garber was intentionally vague about the team’s start date, with the stadium plan being a key component of that decision. Atlanta United FC will begin play in 2017, with Los Angeles FC starting in 2018; the Miami franchise, led by David Beckham, likely will kick off even later. It would make sense for Minnesota, the only one of the four expansion sides already playing soccer, to join in 2017, thereby keeping an even number of teams in the league.

Even though the Loons have a team already on the field, joining MLS is not as simple as taking the same players and playing a different schedule. MLS is technically set up as a single central entity, so players coming into the league are allocated to teams via an arcane set of rules. One of these is the “discovery process,” in which a team is allowed to list seven non-public claims on players who aren’t college players, former MLS players, or U.S. national team stars. These claims can be submitted a year in advance — meaning that 2017 expansion teams would submit their lists this winter.

Interestingly, should an MLS team have a current claim on a United player — striker Christian Ramirez and defender Justin Davis might be the leading candidates — it would be possible that Minnesota would have to let the player go to a new team, or make a trade to keep the player. This may also apply to players with MLS experience, like Kalif Alhassan.

The discovery process is far from the only mechanism for the new expansion teams to acquire players, of course. For one, the league will hold an expansion draft the winter before Minnesota begins play; for another, expansion teams get the first picks in the annual college SuperDraft in January before the season. Scouting of both MLS and college players would need to be a priority for Minnesota next year, as those two areas will form the core of United’s first MLS roster.

There are allocation mechanisms beside those, as well — so many that, when NYC FC and Orlando City joined the league last year, they held a meta-draft, in which the two picked which would go first in eight different allocation rankings. It so confused NYC FC coach Jason Kreis that he exclaimed, “I’ve made a mistake!” while laughing, after he drafted the wrong thing with his second selection. Minnesota will hope to avoid the same confusing mistakes as they begin, even a year in advance, to drive toward MLS.

Socer short takes

• The NWSL announced the league’s 10th franchise Tuesday, the Orlando Pride (think Lions, the nickname of MLS side Orlando City FC). It didn’t take long for Orlando to start making a splash, either — two days later it traded the No. 1 draft pick and two players for star U.S. striker Alex Morgan. Her husband, Servando Carrasco, plays for Orlando City, and she requested the move shortly after the franchise was announced.

•  The Ottawa Fury clinched the NASL fall-season championship on Wednesday, leaving Minnesota with little to play for, standingswise, in its final two home games. It looks very likely that United will travel to New York for the league semifinals on Nov. 7. History does not paint an optimistic picture for Minnesota. The Loons have had no luck on the road against the Cosmos, drawing one game and losing three.

•  On Friday, U.S. Soccer was cleared to host a special Copa America in the United States next summer, with all 10 South American nations and six of the best North American nations, including the U.S., Mexico and Costa Rica.

WEEKEND WATCH GUIDE

Premier League: Chelsea at West Ham, 9 a.m. Saturday, NBC Sports: A win last week could be the beginning of Chelsea’s recovery from a disastrous start to the season. In its way stands West Ham, the league’s most confusing team; the Hammers have away wins against Arsenal, Manchester City and Liverpool but have only one home win despite an easy schedule.

Premier League: Manchester City at Manchester United, 9 a.m. Sunday, NBC Sports: With United’s resurgence under Louis Van Gaal, the Manchester rivalry has some sting in it again. Just two points separate the teams at the top of the standings, and with the season already a quarter over, it would appear that only Arsenal has a chance to keep the title out of Manchester.

Bundesliga: Schalke at Monchengladbach, 11:30 a.m. Sunday, Fox Sports 1: After an impossibly awful start to the season, in which it lost its first five games of the season, Monchengladbach has won four in a row and recovered to the middle of the German standings. Schalke has defender Benedikt Howedes on his way back from injury, a boost for a team already in third place in the Bundesliga.

MLS: Los Angeles at Kansas City, 6 p.m. Sunday, ESPN: Sporting KC will be playing with one eye on the scoreboard, as — depending on San Jose, Seattle, and Portland — it may need to win to be assured of a playoff spot. The Galaxy can guarantee itself a first-round bye in the playoffs with a victory, as well, giving both teams plenty of reason to give their all.